Blot doesn't run with timeshift enabled.
But even if he did, from live TV, REC>>1/Create instant recording... doesn't save the current contents of any existing timeshift segment, it simply starts a recording from that point onwards (plus post-padding).
I think you're referring to REC>>2/Select an event to save..., but that's saving the timeshift buffer's current segment. It doesn't fire off a timer (unless you zap away and choose to do so), it just starts an action to save the timeshift segment at the end of the broadcast event, and a timer is subsequently fired at event end to capture the post-padding. The two recordings are then "welded" at conclusion of the post-padding timer.
Which wouldn't necessarily give the desired behaviour if the event started after the stated EPG event begin time.